Liquid level indication is required for use with tanks containing liquids such as oil tanks for use in heating. The following patents are considered to be of general relevance to the subject matter of the present invention and are not believed to anticipate or render the present invention obvious, whether taken alone or in any combination.
Each of the patents listed below is directed to a liquid level gauge using a float fixed to a rod, in turn, pivotally attached to a sliding rod and a support rod, wherein the position of the sliding rod within a transparent cup disposed outside of the tank indicates the liquid level in the tank.
U.S. Pat. No. 2,889,708 (R. F. Williams) entitled GAUGE describes a threaded flange integral with a nut head for securing the gauge to the tank. The float is described as being an ordinary cork or like float. The gauge is intended to be tamper proof and is locked together by pressure, punch or other form of distortion.
U.S. Pat. No. 2,446,844 (H. Molayer) entitled LIQUID GAUGE discloses a threaded bushing for screwing onto the tank opening. The inverted closed cup is then screwed within the bushing. Washers are used to obtain a tight seal.
U.S. Pat. No. 2,651,200 (B. E. Colburn) entitled TANK GAUGE teaches a gauge that may be used with tank openings of various sizes by having differently sized pipe threadings as part of a plug mounting. The inverted closed cup is then screwed on within the plug mounting.
Canadian Patent No. 454,572 (Edward Olszowka) entitled LIQUID GAUGE describes a gauge which advantages include the ability to provide an indication of the direction of the float and a float which will not absorb moisture. The gauge is held in place by a collar around the tank's opening and includes an annular recess into which the transparent cup fits. Two washers are provided at either end of the cup for sealing.
Canadian Patent No. 447,723 (Alois Kresta) entitled TANK GAUGE FOR OIL AND OTHER LIQUID discloses a gauge which may be easily and quickly placed in the tank and secured with a liquid- and gas-tight seal. The base of the gauge member has an expandable collar adapted for insertion into the bore of the tank, the collar being expandable by applying external pressure. The transparent gauge cup is held in place by counterbored circular recess in the gauge.
Canadian Patent No. 475,098 (Joseph F. Wilhelm) entitled GAUGES teaches a gauge having a plug body with threads for securing to the tank opening and having a flange for tightening with a wrench. The transparent cup is snugly fitted to the gauge and is protected by a casing. Washers or gaskets are used to obtain a tight seal.
U.S. Pat. No. 2,255,310 (J. D'Arcey) OIL GAUGE describes an annular plug which engages (preferably by threadings) a boss on the tank. The plug includes an internal flange adapted to receive a wrench for tightening. The inner face of the plug is threaded to receive a nipple on the end of which rests an annular plate which supports a transparent head. The plug and nipple may alternatively be replaced by a single nipple. A dial is also provided for calibration. Gaskets are used to provide an air-tight seal.
U.S. Pat. No. 2,240,669 (M. P. Russo) LIQUID GAUGE discloses a liquid gauge readily securable to a cap or collar threaded into a brushing or neck member secured to the tank. The transparent cup is encased within a protective casing and attached to a socket of the gauge. An air-tight seal is provided by gaskets or washers.
The above-listed patents relate to liquid level gauges using a float, arrangement of pivoting rods and sliding rod indicating the liquid level using a transparent cup resting outside of the tank.
Various ways of attaching the gauge to the tank are proposed in the prior patents including the use of a threaded base for engagement with the threaded tank aperture. However, none of the enclosed patents teaches a configuration which is described and claimed herein which affords the advantages which will become apparent hereinbelow.
The primary cause of accelerated domestic oil tank corrosion is chlorine-laden water and therefore it is beneficial to prevent such water from entering into domestic heating oil tanks. The liquid level indicator of the present invention is purposed to attain such prevention while operating as an effective indicator. Certain prior devices use a transparent cup which is set into the centre of the base block which has a well effect and thus retains chlorine-laden water and allows such water to enter into the tanks. Such configuration provides less support to the transparent cup which may crack or break easily under normal conditions.